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Nighthawk CO detector from 1996, fix?

topaztopaz Posts: 9Member
I have a CO detector which was given to me. It doesnt appear to be functional as it reads ---. and 0 when I press the test button. Is the sensor replaceable?
I am fairly electronics literate, spent three years in an EE program once, had to drop out for financial reasons. Have a small electronics bench and all the major tools. logic analyzer, bench multimeter, scope, siggen/AWG . Hoping to get a meter with PPM resolution which will last for a few years. Does anybody know the replacement cost of the sensor?


  • HVACNUTHVACNUT Posts: 2,753Member
    Probably a lot more than a new CO detector when you factor in your labor.
    Why? Just for the fun of it?
    Buy a new one. Fix the old one. Now you have two. Win win.
  • DZoroDZoro Posts: 996Member
    Normally I don't tell people to throw it away, but. This is a safety device that you need working properly. I have seen way too many 5year and older ones not alarming people. Had one last week, retired fireman's house, filled with 80ppm CO 2hours after the boiler was shut down, his detector was 7 years old.
    Buy a new one write on it a replacement date 5years from now.
  • topaztopaz Posts: 9Member
    edited December 2018
    Will definitely do that.

    Do you know of a good one that also is not super expensive, that also gives a readout in ppm? It seems as if there are a lot that give a digital reading now.
  • HVACNUTHVACNUT Posts: 2,753Member
    The good ones are hardwired combo CO/smoke detectors with battery backup.
    The utility near me used to recommend the Kidde Nighthawk. Dont know what is best now as far as plug ins go.
  • topaztopaz Posts: 9Member
    Thank you! My wife beat me to the punch and ordered two, so it seems like 'great minds think alike' :)
  • LeonardLeonard Posts: 840Member
    edited December 2018
    I have an OLD Nighthawk too, displays 0 till you press test , then something like 860 ppm, think the electro chemical sensor modual is only rated for ~ 5 years.

    When I asked for one with a ppm display guys here recommended this one. Held off ordering till I needed enough other stuff to get free shipping
  • topaztopaz Posts: 9Member
    We just got a new one. (actually two different brands, both high rated) It seems to be pretty hard to get it to register. We finally got it to by putting it in a plastic bag that we captured some smoke into. That registered at around 100 ppm for one and 74 ppm for the other.

    Bringing it outside and holding it above a car exhaust and holding it above a gas stove with a burner running didnt register! Maybe that was for too short of a time?
  • neilcneilc Posts: 752Member
    There should be a "Peak" level button,
    which you can push, and it will display readings 0~30 ish,
    if the peak or detector hasn't seen higher levels.
    There should also be a reset button to go back to zero.
    This is all in the instructions.
  • LeonardLeonard Posts: 840Member
    edited December 2018
    Gas stove might have lot of CO2, but little CO.

    Might need exhaust from a cold engine ( 1-st couple minutes of running). After car catalytic converter has warm up to the point it fires off it actually reduces CO content of the air, if car is in a closed garage.

    Actually test data.... a guy ran a modern Toyota in a 2 stall garage and used CO dectotor to measure and graph up garage CO content over ~ 15 minutes. At first it rose then it dropped off.
    Green line in garph.
    post 172 of
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